Children with diagnosed nut allergy are commonly instructed to avoid all nuts, in order to minimise the possibility of contact through contamination from other nuts, and in order to lessen the likelihood of developing a new allergy.

Scientists from Nutrition and Dietetic Paediatrics, University Hospital of Leicester, UK, have used their ability to diagnose more accurately the precise nut allergy, to provide food challenges to nut allergic children in order to determine whether they have sensitivity to more than one type of nut. The aims are to prevent unnecessary dietary restriction, to reduce the risk of anaphylaxis later in life simply due to being uninformed, and to reduce anxiety around nuts.

Over a five-year period they administered homemade biscuits containing nuts in visually increasing, measured doses to 145 children. They found that of those with peanut allergy challenged to treenuts, none of the 72 who tested negatively to skin prick tests (PTs) reacted to the food challenge, whilst seven of the 22 who had positive PTs did. In patients with treenut allergy, 3 out of 38 who had negative PT results reacted, and 5 of 13 with positive PT results reacted.

They conclude that children with peanut allergy who have negative PTs to treenuts have no co-existing allergy, but are at risk of treenut allergy where PTs were positive. But children with treenut allergies were at risk of having co-existing peanut or other treenut allergy whether the PTs were positive or negative. Oral challenges can clarify allergy status, and can show where co-existing allergies may be found.

Source: Pediatric Allergy and Immunology

First published in September 2011

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